1. Field of the Invention
The present invention relates to a magnetic recording medium having a magnetic layer containing mainly a magnetic or magnetizable powder and a binder. 2. Brief Description of the Prior Art
As a binder used for binding the magnetic or magnetizable powders to the supporting base for conventional magnetic recording medium such as magnetic tapes have been employed, for example, vinyl chloride-vinyl acetate-vinyl alcohol copolymers. This binder, however, cannot provide sufficient properties of decreasing the amount of the magnetic or magnetizable powders rubbing off during the operation of the magnetic recording medium and, at the same time, has a problem with a resistance to chemicals.
It is also known of another conventional binder extensively employed, which is treated on its surface with a silane coupling agent for the purpose of coupling the interfaces of the magnetic or magnetizable powders with the agent. In this case, the magnetic or magnetizable powders are bound through the silane coupling agents to the binder so that a problem with an increase in the rubbing-off amount of the magnetic or magnetizable powders or particles may be solved to some extent, but such binder cannot provide a sufficient physical strength and resistance to chemicals.
It has also been proposed to employ as a binder a compound which is sensitive to radiation, which can form a bridge structure with the magnetic or magnetizable powders in the binder upon irradiation of radiation so that physical strengths are to be improved, but it creates new problems which should be solved because the cured materials are too hard and nevertheless brittle.